The overall objective of this project is to define the development and pathogenesis of immune complex disease in guinea pig lungs. Current efforts are devoted to determining the source of the reactants (i.e., antibodies and complement) which mediate this disease. Sera and lung lavage fluids from actively or passively (serum transfer) immunized animals before and at intervals after aerosol challenge with homologous immunogen will be tested for antibody and complement activity. The relative contribution of the classical and alternative complement pathways to the production of this pulmonary injury will be analyzed in C4-deficient guinea pigs. Immunofluorescent techniques will be used to visualize the distribution of the inhaled immunogen in the lung. Future research will focus on the kinetics of the vasculature to lung transfer of antibodies which occurs during the initial stage of this pneumonopathy. Radiolabeled IgG1 and/or IgG2 antibodies will be used to passively immunize animals for this study. Finally, studies will be initiated to determine whether the immune complexes are formed in the circulation of lungs of affected animals. Actively immunized guinea pigs will be intratracheally challenged with radiolabeled immunogen and the antigen antibody complexes will be detected by an antiglobulin coprecipitation technique.